$A$ metal cube is given a positive charge $(+Q)$. Which of the following statements is true?

Two charged metallic spheres are joined by a very thin metal wire. If the radius of the larger sphere is four times that of the smaller sphere,the electric field near the larger sphere is

Two spheres $A$ and $B$ are kept very near to each other. $A$ is negatively charged and $B$ is earthed. The true statement is:
$(A)$ Charge on $B$ is zero
$(B)$ Potential at $B$ is zero
$(C)$ Charge is uniformly distributed on $A$
$(D)$ Charge is non-uniformly distributed on $A$

What is a Van de Graaff generator? Explain its principle.

Write important results regarding the electrostatics of conductors.

Two spherical conductors $A$ and $B$ of radii $R_1$ and $R_2$ are charged to the same potential and placed at a distance $d$ apart. If these spheres are connected by a conducting wire,what is the ratio of the magnitudes of the electric fields at the surfaces of $A$ and $B$ in the equilibrium state?